New Polymeric Bead Compositions

ABSTRACT

The present invention is a polymeric bead composition. More particularly the present invention is directed to a new polymeric bead composition formed by suspension polymerization processes from a phosphorous acid containing monomers.

The present invention is a polymeric bead composition. More particularlythe present invention is directed to a new polymeric bead compositionformed by suspension polymerization processes from a phosphorous acidand its salt containing monomers.

Various monomers have been polymerized in the art to make polymericbeads. Typically the processes to make these polymeric beads arelaborious and require expensive monomer materials. Additionally when afunctional polymer is desired additional functionalization steps areoften needed to functionalize the resultant polymer. This adds to theexpense, waste generation and inefficiency of the polymer manufacturingprocess.

To attempt to minimize waste and solve these problems of cost andinefficiency in a single step process, a class of monomers, has beenused in the art that does not need the additional steps offunctionalization because the monomer itself contains the functionalgroups. Phosphorous acid containing monomers, such as phosphoalkylmethacrylate ester have been used for this purpose. Typically thesemonomers are polymerized by an emulsion polymerization method asdisclosed in U.S. Pat. No. 4,110,285. The emulsion polymerized materialstypically have very low levels of acid containing monomers andcross-linking monomers. The problem with this method is that it producespolymeric beads having an average particle size of less than 1 μm. Someapplications require the use of large beads or polymers formed having anaverage particle size greater than 30 μm.

The present invention solves this problem by providing an improvedpolymeric bead comprising an acid monomer of phosphoalkyl methacrylateester wherein the beads have an average particle size of greater than 30μm.

The present invention provides A polymeric bead composition comprising:

i) at least 20-99.9 weight percent phosphorous-containing acid monomerand

ii) an average particle size of 30 to 1000 μm.

The invention further provides the polymeric bead composition of claim 1wherein the polymeric bead is prepared by

i) forming a suspension,

wherein the suspension comprises at least one phosphorus-containing acidmonomer an aqueous medium, a free-radical initiator and a suspendingagent;

ii) and allowing the monomers to polymerize until they have formedwater-insoluble polymeric beads.

The monomer useful in the present invention to make improved polymericbeads is a phosphorus-containing acid monomer, the monomer containing atleast one ethylenic unsaturation and a phosphorus acid group. Thephosphorus-containing acid monomer may be in the acid form or as a saltof the phosphorus acid groups. Examples of phosphorus acid monomersinclude:

wherein R is an organic group containing an acrylic, methacrylic,styrenic, acryloxy, methacryloxy, styryl, aryl, or a vinyl group; and R′and R″ are independently selected from H and a second organic group. Thesecond organic group may be saturated or unsaturated.

Suitable phosphorus acid monomers include dihydrogenphosphate-functional monomers such as dihydrogen phosphate esters of analcohol in which the alcohol also contains a polymerizable vinyl orolefinic group, such as allyl phosphate, mono- or diphosphate ofbis(hydroxy-methyl) fumarate or itaconate, derivatives of (meth)acrylicacid esters, such as, for examples phosphates ofhydroxyalkyl(meth)acrylates including 2-hydroxyethyl (meth)acrylate,3-hydroxypropyl (meth)acrylates, and the like. Other suitablephosphorous acid monomers include CH2=C(R)—C(O)—O-(R1O)n—P(O)(OH)2,where R=H or CH3 and R1=alkyl, such as SIPOMER™ PAM-100, SIPOMER™PAM-200, SIPOMER™ PAM-300, and SIPOMER™ PAM-4000, available from Rhodia,Inc. PEM is the phosphate ester of hydroxyl ethyl methacrylate monomer.

Other suitable phosphorus acid monomers are phosphonate functionalmonomers, disclosed in WO 99/25780 A1, and include vinyl phosphonicacid, allyl phosphonic acid, 2-acrylamido-2-methylpropanephosphonicacid, α-phosphonostyrene, 2-methylacrylamido-2-methylpropanephosphonicacid. Further suitable phosphorus functional monomers are HarcrossT-Mulz 1228 and 1,2-ethylenically unsaturated (hydroxy)phosphinylalkyl(meth)acrylate monomers, disclosed in U.S. Pat. No. 4,733,005, andinclude (hydroxy)phosphinylmethyl methacrylate. Preferred phosphorusacid monomers are dihydrogen phosphate monomers, which include2-phosphoethyl (meth)acrylate, 2-phosphopropyl (meth)acrylate,3-phosphopropyl (meth)acrylate, and 3-phospho-2-hydroxypropyl(meth)acrylate. Preferred are 2-phosphoethyl (meth)acrylate,2-phosphopropyl (meth)acrylate, 3-phosphopropyl (meth)acrylate,3-phospho-2-hydroxypropyl (meth)acrylate, SIPOMER™ PAM-100, and SIPOMER™PAM-200.

In the present invention, the acid monomer can be polymerized in itsoriginal form. Preferably the acid monomer is in protonated form.Alternatively the phosphorus-containing acid monomer may be complexedwith metals prior to polymerization. For example a metal may becomplexed with the phospho moiety of the acid monomer. Thephosphorus-containing acid monomer of the present invention could be inthe protonated acid form prior to polymerization or thephosphorus-containing acid monomer complexed with metal prior topolymerization. The metal complexed monomers employ a multivalent metalion which binds more than one phosphate containing monomer. Thisphosphorus-containing acid monomer is present in an amount ranging from20-99.9%, alternatively from 40-99.9%, and further alternatively70-99.9% by weight of the total monomeric mixture. One particularlysuitable phosphorus-containing acid monomer within this broad class ofmonomers of the present invention is the acid monomer phosphoethylmethacrylate.

Crosslinking monomers useful in the present invention include bothwater-insoluble multiethylenically unsaturated monomers, including:aromatic crosslinkers such as divinylbenzene, trivinylbenzene,divinylnaphthalene, divinyltoluene, divinylchlorobenzene, diallylphthalate, divinylxylene, divinylethylbenzene. trivinylnaphthalene andpolyvinylanthacenes; non aromatic crosslinkers such as diethyleneglycoldivinyl ether, trimethylolpropane trimethacrylate, diethylene glycoldivinyl ether, diethylene glycol dimethacrylate, ethylene glycoldiacrylate, neopentyl glycol dimethacrylate, pentaerythritol tetra-andtrimethacrylates, allyl acrylate, divinyl ketone,N,N′-methylenediacrylimide, N,N′-methylene-dimethacrylimide,N,N′-ethylenediacrylimide, diallyl maleate, diallyl fumarate, diallylsuccinate, diallyl carbonate, diallyl malonate, diallyl oxalate, diallyladipate, diallyl sebacate, diallyl tartrate, diallyl tricarballylate,triallyl aconitate, triallyl citrate; the polyallyl and polyvinyl ethersof glycol, glycerol and pentaerythritol; aralkyl crosslinking monomerssuch as bisphenol-A dimethacrylate, and the polyallyl and polyvinylethers of resorcinol; and mixtures thereof. Preferred crosslinkingmonomers are divinylbenzene, trimethylolpropane trimethacrylate,trimethylolpropane triacrylate, hexamethylene-bis-methacrylamide anddiethylene glycol divinyl ether, and mixtures thereof. The crosslinkingmonomers herein expressly exclude phosphorus containingmultiethylenically unsaturated monomers such as multiethylenicallyunsaturated PEM diesters, and the like. The crosslinking monomers arepresent at a level from 0 to 30%, alternatively from 2-20% and furtheralternatively from 4 to 10%, by weight, of the total monomer mixture.

Other monoethylenically unsaturated monomers may be present in a minoramount in the monomer mixture. The non-water-soluble monomers useful inthe present invention include those which are copolymerizable with thecombination of the acid monomer and the crosslinking monomer. Theseinclude both aromatic and aliphatic monomers having monoethylenicunsaturation, including those which are substituted with functionalgroups other than the ethylenic groups. A single type or combination ofother monomethylenically unsaturated monomers may be present.

Polymerization initiators useful in the present invention includemonomer-soluble initiators such as peroxides, hydroperoxides and relatedinitiators, for example benzoyl peroxide, tert-butyl hydroperoxide,cumene peroxide, tetralin peroxide, acetyl peroxide, caproyl peroxide,tert-butyl perbenzoate, tert-butyl diperphthalate and methyl ethylketone peroxide. Also useful aredi(4-tert-butyl-cyclohexyl)peroxidicarbonate and azo initiators such asazodisobutyronitrile, azodiisobutyramide,2,2′-azo-bis-(2,4-dimethylvaleronitrile), azo-bis-(amethylbutyronitrile)and dimethyl, diethyl or dibutyl azo-bis-(methylvalerate). The preferredinitiator is di(4-tert-butyl-cyclohexyl)peroxidicarbonate. Theinitiators are preferably used at a level of from 0.01 to 5% by weight,alternatively from 0.01% to 3% by weight, and preferably from 0.01% to2% by weight, based on the total weight of the monomers. Combinations ofinitiators may be used.

Salts useful for reducing solubility of the water-soluble monomer in theaqueous phase are water-soluble, non-reactive inorganic salts includingwater-soluble, non-reactive inorganic salts of a monovalent, divalent oraluminum cation and a monovalent or divalent anion, for example sodium,potassium, lithium and ammonium salts of chloride, bromide, iodide,sulfate, carbonate and nitrate, and the magnesium and calcium salts ofchloride, bromide, iodide and nitrate. Preferred salts are sodiumchloride, sodium sulfate and sodium nitrate. The salt is dissolved inthe aqueous medium at levels from 5 weight percent, based upon the totalweight of the aqueous phase, to saturation of the salt in the aqueousphase. The term, “non-reactive”, as applied to the salts herein, meansthat the salt does not react chemically with water, the monomers or thepolymers formed from the monomers.

Dispersants or suspending agents useful in the present invention arenonionic surfactants. Examples of such suitable nonionic surfactantsinclude but are not limited to partially hydrolyzed polyacrylamide,polyvinyl alcohol, kaolin, tricalcium phosphate, hydroxyalkyl cellulose,and the like, and mixtures thereof.

The process of the present invention comprises forming a suspension ofthe monomer mixture, including the acid monomer and from 0 to 30 weightpercent, based on the total monomer weight, of crosslinking monomer, andoptionally a second monoethylenically unsaturated monomer, in an aqueousmedium containing from 5 weight percent to saturation of water-soluble,non-reactive inorganic salt in the presence of free-radical initiator,for example from 0.1 to 5 weight percent of monomer-soluble,free-radical initiator, and from 0.01 to 4 weight percent of nonionicsurfactant-type dispersant; establishing polymerization conditions inthe suspension, and allowing the monomers to polymerize until they haveformed water-insoluble particles. The water-insoluble particles may thenbe separated from the aqueous phase.

The monomer phase forms spherical droplets within the aqueous phase;these are preferably kept suspended by agitation, but other techniquesfor maintaining suspension which will be readily apparent to thoseskilled in the art may be employed, for example using a static mixer, orsuspending the droplets in a liquid stream moving opposite to thedirection in which the droplets tend to move by their density. Thepolymerization reaction occurs within the suspended monomer droplets,and is initiated by establishing a temperature in the droplet which isat least as great as a decomposition temperature of the polymerizationinitiator which will allow polymerization of the monomers to occur. Areasonable lower temperature for polymerization is about 40° C.; oneskilled in the art will realize that if an initiator is selected havinga higher decomposition temperature, the minimum temperature will bechosen according to the decomposition temperature of the actualinitiator used. The upper limit for the polymerization reaction is theboiling temperature of the suspending medium; the medium employed hereinis aqueous, so at atmospheric pressure the maximum temperature will be100° C., and higher temperatures may be used at higher pressures. Alower temperature may be advantageous to prevent decomposition of one ormore of the monomers or the dispersant, or for other reasons which willbe apparent to one skilled in the art.

The process of the present invention may be used for preparing both geland macroporous resins. For the preparation of macroporous resins aporogen is commonly used. Porogens are substances in which the monomersare soluble but the resulting polymer is insoluble, and which willdissolve the monomers within the suspended droplet, without reactingwith the other components of the polymerization mixture. Thus, for thepresent process, sufficient porogen must remain within the suspendeddroplet to dissolve the monomer mixture at least partially, and tocreate the pores within the particle as the polymer forms Examples ofuseful porogens include, e.g., C₇-C₁₀ hydrocarbons, C₃-C₁₀ halogenatedhydrocarbons, C₄-C₁₀ ketones, C₃-C₁₀ alcohols and combinations thereof.Especially preferred porogens include methyl isobutyl ketone (MIBK),diisobutyl ketone (DIBK), methyl isobutyl carbinol (MIBC),1,2-dichloropropane, toluene (tol), xylenes, isooctane, chlorobenzeneand n-butyl acetate. When the resin beads of the present invention aremacroporous they have a resultant average particle size of from 30 μm to1000 μm, preferably from 300 to 800 gm, more preferably from 400 to 700μm.

The following examples are presented to illustrate representativeembodiments of the present invention. All ratios and percentages givenherein are by weight unless otherwise specified, and all reagents usedin the examples are of good commercial quality unless otherwisespecified.

EXAMPLES

Examples 1 to 6 used the following charges but changing monomer ratios:

In a 2 liter laboratory reactor 390 g deionized water, 138 g NaCl, 2.6 gof sodium carboxymethyl cellulose were charged under stirring conditionat 200 rpm. In a monomer preparation tank 5.8 g ofdi(4-tort-butyl-cylcohexyl) peroxidicarbonate and Glacial MethacrylicAcid (GMAA), PEM, Divinyl Benzene (DVB) and were added according totable 1 for the different formulations. The agitation was stopped in thepolymerization reactor and the monomer mix was charged to the reactor.The reactor was then stirred at 150 rpm during the run. The temperatureprofile was room temperature for 30 minutes, heated to 58° C. and heldfor 6 hours and then heated to 97° C. and held for 4 hours. The reactionwas then cooled down to room temperature. The lot was washed with excesswater, wet screened thru 20 on 50 mesh screens, Buchner dried andpacked. 390 ml of final product was obtained

TABLE 1 Monomer charges and properties. Example Number: 1 2 3 4 5 6 %PEM (*) 50 50 25 100 75 50 GMAA (g) 150 150 50 0 75 150 PEM (g) 150 150250 300 250 150 DVB (g) 24 24 12 25 25 25 Moisture Hold Capacity (%) 3739 75 58 43 42 Weight Exchange 5.1 5.2 6.1 4.5 6.3 7.6 Capacity (eq/kg)Mean Particle Size (um) 365 365 328 404 554 346 (*) % for PEM to GMAAratio charged.

1. A polymeric bead composition comprising: i) at least 20-99.9 weightpercent phosphorous-containing acid monomer; and ii) an average particlesize of 30 to 1000 μm.
 2. The polymeric bead composition of claim 1wherein the phosphorous-containing acid monomer is a monomer selectedfrom the following:

wherein R is an organic group containing an acrylic, methacrylic,styrenic, acryloxy, methacryloxy, styryl, aryl, or a vinyl group; and R′and R″ are independently selected from H and a second organic group; andfurther wherein the second organic group may be saturated orunsaturated.
 3. The polymeric bead composition of claim 1 wherein the Ris an acrylic, methacrylic or styrenic group
 4. The polymeric beadcomposition of claim 1 wherein the R is an acrylic or methacrylic group.5. The polymeric bead composition of claim 1 wherein thephosphorous-containing acid monomer is in protonated form.
 6. Thepolymeric bead composition of claim 1 wherein the polymeric bead isprepared by i) forming a suspension, wherein the suspension comprises atleast one phosphorus-containing acid monomer an aqueous medium, afree-radical initiator and a suspending agent; ii) and allowing themonomers to polymerize until they have formed water-insoluble polymericbeads.
 7. The polymeric bead composition of claim 4 further wherein thesuspension further comprises a crosslinking monomer in an amount from 0to 30 weight percent.
 8. The polymeric bead composition of claim 4wherein the phosphorous-containing acid monomer is in protonated form.